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Biomedical subjects

Feng Gao

Publications and source records attributed to Feng Gao.

At least 199 records · Page 11Linked to original sources
PubMed2004

Single agent gefitinib as first line therapy in patients with advanced non-small cell lung cancer: Washington University experience.

Gefitinib has modest activity with an overall response rate of 11-18% in patients with metastatic non-small cell lung cancer (NSCLC) who have had progressive disease following platinum containing chemotherapy. However, the efficacy of gefitinib in previously untreated metastatic NSCLC is not known. We retrospectively analyzed the efficacy of gefitinib as a first line therapy in 26 patients with advanced NSCLC enrolled in the expanded access program. Patients received gefitinib 250 mg a day orally if they had a poor performance status (PS) or if they refused cytotoxic chemotherapy. Treatment was continued as long as there was no evidence of disease progression or unacceptable treatment related toxicities. The characteristics of 25 evaluable patients enrolled between the period of May 2001 and August 2002 include: 15 women, 10 men; median age 73 years (range 56-86), 81% had an ECOG performance status of two. Only one patient had a partial response and 32% had stable disease as their best response for a disease control rate of 36%; 32% of patients had disease control lasting 5 months or longer. The median overall survival and progression-free survival (PFS) were 14.1 and 2.9 months, respectively. Toxicities were minimal and included rash and diarrhea. Gefitinib was well tolerated and had interesting activity in previously untreated patients with advanced NSCLC.

Aged↗
PubMed2004

Effect of diazoxide on regulation of vesicular and plasma membrane GABA transporter genes and proteins in hippocampus of rats subjected to picrotoxin-induced kindling.

Epileptiform discharges and behavioral seizures may be the consequences of excess excitation from inadequate inhibitory effects associated with gamma-aminobutyric acid (GABA). GABA is taken up and accumulated in synaptic vesicles by the action of vesicular GABA transporter (VGAT) before its release into the synaptic cleft, and removed from synaptic regions by the action of transporter proteins GABA transporter-1 (GAT-1) and GABA transporter-3 (GAT-3). In this experiment, the effects of diazoxide (DIZ) on the VGAT, GAT-1 and GAT-3 mRNA and protein levels in hippocampus, and on the seizure activities of picrotoxin (PTX)-induced kindling rats were observed. DIZ caused increase in the quantity of VGAT mRNAs and proteins, and down regulation of GABA transporters GAT-1 and GAT-3 mRNAs and proteins after the PTX re-kindling. Furthermore, DIZ produced not only a prompt but also a later suppression of PTX-induced seizures. Although DIZ has effects on ATP-sensitive potassium (K(ATP)) channels when measured in vitro, our study suggests that additional mechanisms of action may involve the regulation of GABA transporters, which may aid in understanding epileptogenesis and inform investigators about future design and development of K(ATP) channel openers to treat epilepsy.

Animals↗
PubMed2004

Cetyltrimethylammonium bromide sensitized resonance light-scattering of nucleic acid--Pyronine B and its analytical application.

This is the first report on the determination of nucleic acids with Pyronine B (PB) sensitized by cetyltrimethylammonium bromide (CTMAB) with resonance light-scattering (RLS) technique. Under the experimental conditions (1 x 10(-5) mol l(-1) PB, 1 x 10(-5) mol l(-1) CTMAB, pH 7.4, at room temperature, ionic strength 0.02 mol l(-1) NaCl), the interaction of PB with DNA sensitized by CTMAB results in enhanced RLS signals at 328 and 377 nm in the enhanced regions. It was found that the enhanced RLS intensity at 328 nm was proportional to the concentration of DNA in the suitable ranges. The linear range of this assay is 0.0-1.2 microg ml(-1) for calf thymus, 0.0-0.8 microg ml(-1) for fish sperm DNA (fsDNA), and 0.04-1.4 microg ml(-1) for yeast RNA, respectively. The detection limits (3 sigma) are 6.1 ng ml(-1) for calf thymus DNA (ctDNA), 11.2 ng ml(-1) for fish sperm DNA, and 8.6 ng ml(-1) for yeast RNA, respectively. Six synthetic samples were determined satisfactorily. This method is simple, rapid and the dye is inexpensive and stable.

Cetrimonium↗
PubMed2004

Panniculectomy: improving lymph node yield in morbidly obese patients with endometrial neoplasms.

OBJECTIVE: Panniculectomy has been used to facilitate pelvic surgery in obese women. The goal of this study was to determine the effect of panniculectomy on staging adequacy and lymph node yield in obese women with endometrial carcinoma undergoing staging laparotomy. METHODS: A retrospective review of patients with endometrial neoplasms who underwent panniculectomy at the time of hysterectomy was performed. For each subject, two control patients were matched by body mass index (BMI). RESULTS: Twenty-seven endometrial cancer patients who underwent panniculectomy at the time of staging were identified. Panniculectomy was successfully performed in all 27 patients. While the mean number of pelvic nodes was statistically similar between the two groups (16.2 vs. 13.7) (P = 0.199), the paraaortic node count was higher in patients who underwent panniculectomy (4.3 vs. 2.9) (P = 0.032). A paraaortic node dissection was not feasible in 3 (11.1%) of the panniculectomy patients and in 11 (20.4%) of the controls (P = 0.365). There were no differences in intraoperative or postoperative complications or in survival between the two groups. CONCLUSION: Among obese women with endometrial cancer, panniculectomy is well tolerated, feasible, and associated with acceptable morbidity. While the clinical significance of an increased paraaortic node count is uncertain, our findings suggest that panniculectomy may enhance operative exposure and facilitate endometrial cancer staging.

Adenocarcinoma↗
PubMed2004

Gene therapy for liver transplantation using adenoviral vectors: CD40-CD154 blockade by gene transfer of CD40Ig protects rat livers from cold ischemia and reperfusion injury.

Liver injury induced by ischemia/reperfusion (I/R) is the prime factor in delayed or loss graft function following transplantation. CD4+ T lymphocytes are key cellular mediators of antigen-independent inflammatory response triggered by I/R. We attempted to modulate rat liver I/R injury by targeted gene therapy with CD40Ig, which blocks the CD40-CD154 costimulation pathway. One hundred percent of Ad-CD40Ig-pretreated orthotopic liver transplants (OLTs) subjected to 24 h of cold (4 degrees C) ischemia survived > 14 days (vs 50% in untreated/Ad-beta-gal groups). Ad-CD40Ig treatment decreased sGOT levels and depressed neutrophil infiltration, compared with controls. These functional data correlated with histological Suzuki's grading of hepatic injury, which in untreated/Ad-beta-gal groups showed severe necrosis (> 60%) and moderate to severe sinusoidal congestion; the Ad-CD40Ig-pretreated group revealed minimal sinusoidal congestion/necrosis. Unlike in controls, OLT expression of mRNA coding for IL-2/IFN-gamma remained depressed, whereas that of IL-4/IL-13 reciprocally increased in the Ad-CD40Ig group. Ad-CD40Ig reduced frequency of TUNEL+ cells and pro-apoptotic Caspase-3, but enhanced antioxidant HO-1 and anti-apoptotic Bcl-2/Bcl-xl expression. Thus, prolonged blockade of CD40-CD154 by CD40Ig exerts potent cytoprotection against hepatic I/R injury. These results provide the rationale for a novel gene therapy approach to maximize the organ donor pool through the safer use of liver transplants exposed to prolonged cold ischemia.

Adenoviridae↗
PubMed2004

Interleukin 13 gene transfer in liver ischemia and reperfusion injury: role of Stat6 and TLR4 pathways in cytoprotection.

Ischemia and reperfusion injury (IRI) represents the major problem in clinical liver transplantation. We have shown that transcription of signal transducer and activator of transcription 4 (Stat4) plays a key role in the mechanism of hepatic IRI, whereas local induction of interleukin 13 (IL-13) is cytoprotective. The disruption of innate Toll-like receptor 4 (TLR4) signaling prevents mouse livers from undergoing fulminant IRI. This study analyzes in vivo interplay between innate (TLR4) and adaptive (Stat6) immunity in Ad-IL-13 (recombinant adenovirus encoding IL-13) cytoprotection in hepatic IRI. Using a partial 90-min lobar warm ischemia model, groups of wild-type and Stat6-deficient knockout mice were assessed for the severity of hepatocellular damage at 6 hr postreperfusion. Unlike in wild-type mice, treatment of Stat6 knockout recipients with Ad-IL-13 failed to improve hepatic function/histology. The expression of mRNAs encoding tumor necrosis factor alpha/IL-1 beta and IL-2/interferon gamma remained depressed in the wild-type plus Ad-IL-13 group, but not in the Stat6 knockout plus Ad-IL-13 group. Ad-IL-13 increased antioxidant heme oxygenase 1 (HO-1) expression and prevented TLR4 activation in livers of Stat6-competent (wild-type) mice. In contrast, low HO-1 expression and enhanced TLR4 expression were recorded in Stat6 knockout recipients despite Ad-IL-13 therapy. Thus (1) Stat6 is required for Ad-IL-13 to prevent IRI, and (2) depression of TLR4 activation is Stat6 dependent. In conclusion, the Stat6 pathway operates as a key negative regulator in the hepatic inflammatory ischemia-reperfusion response. This study outlines requirements for Ad-IL-13 use to maximize the organ donor pool through the use of liver transplants despite prolonged ischemia.

Animals↗
PubMed2004

Complete genome analysis of one of the earliest SIVcpzPtt strains from Gabon (SIVcpzGAB2).

Chimpanzees in west central Africa (Pan troglodytes troglodytes) are known to harbor simian immunodeficiency viruses (SIVcpzPtt) that represent the closest relatives of human immunodeficiency virus type 1 (HIV-1); however, the number of SIVcpzPtt strains that have been fully characterized is still limited. Here, we report the complete nucleotide sequence of SIVcpzGAB2, a virus originally identified in 1989 in a chimpanzee (P. t. troglodytes) from Gabon. Analysis of this sequence reveals that SIVcpzGAB2 is a member of the SIVcpzPtt group of viruses, but that it differs from other SIVcpzPtt strains by exhibiting a highly divergent Env V3 loop with an unusual crown (NLSPGTT) containing a canonical N-linked glycosylation site, an unpaired cysteine residue in Env V4, and two late (L) domain motifs (PTAP and YPSL) in Gag p6. Moreover, phylogenetic analyses indicate evidence of recombination during the early divergence of SIVcpzPtt strains; in particular, part of the pol gene sequence of SIVcpzGAB2 appears to be derived from a previously unidentified SIVcpz lineage ancestral to HIV-1 group O. These data indicate extensive diversity among naturally occurring SIVcpzPtt strains and provide new insight into the origin of HIV-1 group O.

Animals↗
PubMed2004

Atypical squamous cells of undetermined significance in girls and women.

OBJECTIVE: To estimate the outcome of adolescents with atypical squamous cells of undetermined significance (ASC-US) on cytology. METHODS: A review of ASC-US cytology in girls and women aged 10-19 years between 1995 and 1999 was performed. The cytologic and histologic follow-up of each patient was evaluated. The outcome was recorded as the most significant (highest grade) subsequent cervical smear or biopsy. RESULTS: Overall, 535 of 7897 (6.8%) cervical cytologic specimens were reported as ASC-US. The study group consisted of 398 patients for whom pathologic follow-up was available. The mean duration of follow-up was 19 months. Follow-up consisted of repeat cytology in 251 (63%) patients and colposcopy with cervical biopsies and/or endocervical curettage in 147 (37%) of the adolescents. Two hundred fifty-three (64%) adolescents had no pathologic abnormalities on follow-up. Persistent ASC-US was identified in 65 (16%), low-grade squamous intraepithelial lesions/cervical intraepithelial neoplasia (CIN) 1 was found in 44 (11%) and high-grade squamous intraepithelial lesions/CIN 2 or 3 occurred in 36 (9%) of the adolescents. No cases of invasive carcinoma were found. CONCLUSIONS: Among adolescents with ASC-US, the rate of squamous intraepithelial lesions/CIN is similar to that of adults. Although the optimal management of ASC-US in adolescents is unknown, these patients warrant close follow-up. LEVEL OF EVIDENCE: III

Adolescent↗
PubMed2004

New simian immunodeficiency virus infecting De Brazza's monkeys (Cercopithecus neglectus): evidence for a cercopithecus monkey virus clade.

Nearly complete sequences of simian immunodeficiency viruses (SIVs) infecting 18 different nonhuman primate species in sub-Saharan Africa have now been reported; yet, our understanding of the origins, evolutionary history, and geographic distribution of these viruses still remains fragmentary. Here, we report the molecular characterization of a lentivirus (SIVdeb) naturally infecting De Brazza's monkeys (Cercopithecus neglectus). Complete SIVdeb genomes (9,158 and 9227 bp in length) were amplified from uncultured blood mononuclear cell DNA of two wild-caught De Brazza's monkeys from Cameroon. In addition, partial pol sequences (650 bp) were amplified from four offspring of De Brazza's monkeys originally caught in the wild in Uganda. Full-length (9068 bp) and partial pol (650 bp) SIVsyk sequences were also amplified from Sykes's monkeys (Cercopithecus albogularis) from Kenya. Analysis of these sequences identified a new SIV clade (SIVdeb), which differed from previously characterized SIVs at 40 to 50% of sites in Pol protein sequences. The viruses most closely related to SIVdeb were SIVsyk and members of the SIVgsn/SIVmus/SIVmon group of viruses infecting greater spot-nosed monkeys (Cercopithecus nictitans), mustached monkeys (Cercopithecus cephus), and mona monkeys (Cercopithecus mona), respectively. In phylogenetic trees of concatenated protein sequences, SIVdeb, SIVsyk, and SIVgsn/SIVmus/SIVmon clustered together, and this relationship was highly significant in all major coding regions. Members of this virus group also shared the same number of cysteine residues in their extracellular envelope glycoprotein and a high-affinity AIP1 binding site (YPD/SL) in their p6 Gag protein, as well as a unique transactivation response element in their viral long terminal repeat; however, SIVdeb and SIVsyk, unlike SIVgsn, SIVmon, and SIVmus, did not encode a vpu gene. These data indicate that De Brazza's monkeys are naturally infected with SIVdeb, that this infection is prevalent in different areas of the species' habitat, and that geographically diverse SIVdeb strains cluster in a single virus group. The consistent clustering of SIVdeb with SIVsyk and the SIVmon/SIVmus/SIVgsn group also suggests that these viruses have evolved from a common ancestor that likely infected a Cercopithecus host in the distant past. The vpu gene appears to have been acquired by a subset of these Cercopithecus viruses after the divergence of SIVdeb and SIVsyk.

Amino Acid Sequence↗
PubMed2004

Further investigation of simian immunodeficiency virus Vif function in human cells.

Primate lentivirus Vif proteins function by suppressing the antiviral activity of the cell-encoded apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like (APOBEC) proteins APOBEC3G and APOBEC3F. It has been hypothesized that species-specific susceptibilities of APOBEC proteins to Vif proteins may help govern the transmission of primate lentiviruses to new host species. Consistent with this view and with previous results, we report that the Vif proteins of several diverse simian immunodeficiency viruses (SIVs) that are not known to infect humans are not effective inhibitors of human APOBEC3G or APOBEC3F when assessed in transient-transfection experiments. Unexpectedly, this lack of SIV Vif function did not prevent the replication of two vif-deficient SIVs (SIVtan and SIVmnd1; isolated from tantalus monkeys and mandrills, respectively) in a human T-cell line, HUT78, that expresses both APOBEC 3G and APOBEC3F, a finding which demonstrates that some SIVs are partially resistant to the antiretroviral effects of these enzymes irrespective of Vif function. Additional virus replication studies also revealed that the Vif protein of SIVtan is, in fact, active in human T cells, as it substantially enhanced the replication of its cognate virus and human immunodeficiency virus type 1. In sum, we now consider it improbable that species-specific restrictions to SIV Vif function can explain the lack of human infection with certain SIVs. Instead, our data reveal that the species-specific modulation of Vif function is more complex than previously envisioned and that additional (as-yet-unidentified) viral or host factors may be involved in regulating this dynamic interaction between host and pathogen.

APOBEC-3G Deaminase↗
PubMed2004

Unselected mutations in the human immunodeficiency virus type 1 genome are mostly nonsynonymous and often deleterious.

Mutation rates of human immunodeficiency virus type 1 (HIV-1) genomes have been estimated using purified reverse transcriptase or single-round infection system. Since small sequences were used as templates, the overall mutation rates could only be extrapolated and the biological significance of mutations is unknown. For direct estimation of HIV-1 mutation rates and understanding of the potential biological influences of mutations, we obtained 19 complete or nearly full-length proviral genomes from single-round-infected adherent cells of lymphocytes by using a lambda phage library method and a long-range PCR technique. Analysis of 160,000 bp of sequences showed that the overall mutation rate of HIV-1 genomes was 5.4 x 10(-5) per base per replication cycle. On average, 1.1 mutations (range, 0 to 3) were generated in each viral genome during one infection cycle. Inspection of the mutations in the HIV-1 genome revealed that all site mutations within protein-coding regions were nonsynonymous mutations. Among all mutations, half were deleterious (premature stop codon and deletions) and would result in defective genomes. By applying the same system to an HIV-1 genome with a G262A mutation in the thumb region of the reverse transcriptase, a significant increase was observed in deletion and insertion mutation rates but no increase in the overall mutation rate in viral genomes was found.

Base Sequence↗
PubMed2004

Centralized immunogens as a vaccine strategy to overcome HIV-1 diversity.

Genetic variation of HIV-1 represents a major obstacle for AIDS vaccine development. With the amino acid sequence divergence as high as 30% in envelopes between different subtypes among HIV-1 group M viruses, it is unlikely that cross-subtype protection will occur equally well among all subtypes. Computer programs have been used to generate 'centralized' HIV gene sequences: consensus, ancestor or center of the tree. These sequences can decrease the genetic distances between the 'centralized' and wild-type gene immunogens to half of those between any wild-type immuongens to each other. Recent studies demonstrated that an artificial group M consensus env gene is equidistant from any subtype and recombinants. It is biologically functional and preserves antigenicity similar to contemporary Env proteins. Most importantly, the group M consensus Env immunogen can elicit both T- and B-cell responses to wild-type HIV-1 isolates.

AIDS Vaccines↗
PubMed2004

[Role of area postrema of medulla in regulation of rat cardiovascular activity].

OBJECTIVE: To explore the role of area postrema (AP) of medulla in control of cardiovascular functions in rat. METHODS: (1) Sprague Dawley rats were anaesthetized with urethane and pentobarbital and the AP was stimulated by electrical stimulus with intensity of 0.1 mA and frequencies ranged 10 approximate, equals 80 Hz. (2) Excitatory amino acid L-glutamate (L- Glu, 0.1 approximate, equals 0.5 mol/L) was microinjected into AP in urethane anaesthetized rats and the changes of mean arterial pressure (MAP) and heart rate (HR) were recorded. RESULT: (1) When the frequencies of 10 Hz, 20 Hz and 40 Hz were used, the electrical stimulation of AP caused decrease of MAP and HR (P<0.001),while the electrical stimulation with the frequencies of 60 Hz and 80 Hz caused an increase of MAP (P<0.05) but a decrease of HR (P<0.001). (2) Microinjection of L-Glu at 0.1 mol/L had no effect on MAP and HR (P>0.05), but it decreased MAP and HR at 0.15 mol/L (P<0.001, P<0.05). The MAP was increased (P<0.001) but HR (P<0.05) was decreased at the concentrations of 0.2 mol/L and 0.5 mol/L, respectively. CONCLUSION: Alterations of MAP and HR induced by electrical or chemical stimulation on AP of medulla are related to the frequency of electrical stimulation or concentration of L-Glu.

Animals↗
PubMed2004

Propranolol and verapamil inhibit mRNA expression of RyR2 and SERCA in L-thyroxin-induced rat ventricular hypertrophy.

AIM: To study the alteration in the mRNA level of cardiac ryanodine receptor 2 (RyR2) and sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) in L-thyroxin-induced hypertrophy. METHODS: L-thyroxin (500 g/kg) daily was injected for 10 d. RT-PCR was used to determine mRNA expression. RESULTS: An increase in the relative amount of RyR2 (111 %) and SERCA mRNA (65 %) expression was observed in the hypertrophied rats (RyR2: 77+/-11; SERCA: 87+/-10, n=9) compared with the normal rats (RyR2: 36+/-10; SERCA: 53+/-10, n=9). Propranolol was effective to inhibit the increase in RyR2 (51+/-7) and SERCA (63+/-13) mRNA expression in hypertrophied rats, respectively. Verapamil also reduced RyR2 (62+/-5) and SERCA (75+/-8) mRNA expression. CONCLUSION: Both RyR2 and SERCA mRNA level in L-thyroxin-induced cardiac hypertrophy was over-expressed and propranolol or verapamil inhibited the alteration.

Adrenergic beta-Antagonists↗
PubMed2004

[Study on the relationship between [Ca2+]i and the MDR formation in K562/A02 cells].

To explore the relationship of multidrug resistance formation in K562/A02 cells with the intracellular concentration of [Ca(2+)]i, the cytotoxicities of daunorubicin (DNR) were assayed by MTT method, the variations of [Ca(2+)]i of K562 cells and K562/A02 cells after treatment of Tet, DRL and DNR alone or in combination were detected by using Fura-2/AM. The results showed as follows: (1) The cytotoxicities of DNR to cell line K562/A02 were enhanced by 1 micro mol/L Tet or 5 micro mol/L DRL. Their IC(50) was (7.28 +/- 2.06) micro g/ml and (7.58 +/- 3.44) micro g/ml; multiple of their reversal effect was 2.94 and 2.82, but IC(50) of combined Tet and DRL was (1.66 +/- 0.41) micro g/ml. Its reverse effect distinctly increased by 12.9 times. (2) The [Ca(2+)]i in K562/A02 cells were higher than that in K562 cells. (3) One micro mol/L Tet and 5 micro mol/L DRL alone increased the [Ca(2+)]i in K562/A02 cells time-dependently and there was antagonism when both were used. It is concluded that high [Ca(2+)]i is supposed to be a reason of MDR in K562/A02 cells, the action of resistance modifying agents (RMA) in MDR reverse course, however, needs further research.

Alkaloids↗
PubMed2004

[Analysis of methylation status of the promoter of mdr1 gene in K562 and K562/DNR cells].

OBJECTIVE: To analyze the methylation patterns of mdr1 gene promotor in both K562 cell and K562/DNR cells and the relationship between promotor methylation and P-gp expression. METHODS: mdr1 gene expression was analyzed by flow cytometry and RT-PCR, methylation status of the promotor of mdr1 gene by bisulfite-sequencing (including two GC-box). RESULTS: mdr1 gene was found methylated at GC-box and not expressed in K562 cells, but unmethylated and expressed respectively in K562/DNR cells. CONCLUSION: The methylation patterns of mdr1 gene promotor in K562/DNR and K562 cells were different. mdr1 gene silencing was associated with the promotor methylation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

[Reversal effect of tetrandrine in combination with droloxifene on cell line K562/A02 and its correlation with inducted apoptosis].

To study the correlation of the reversal effect of tetrandrine (Tet) in combination with droloxifene (DRL) on multidrug resistant cell line K562/A02 and induction apoptosis, the apoptosis of K562 cells and K562/A02 cells after the treatment of Tet and DRL alone or their combination was detected by flow cytometry (FCM). The results showed 0.62 microg/ml Tet and 1.94 microg/ml DRL alone could induce apoptosis of K562 cells in time-dependent manner after culture for 48 hours. Neither Tet at 0.62 microg/ml nor DRL at 1.94 microg/ml alone could induce apoptosis of K562/A02 cells, but in the combination of them two induced apoptosis of few K562/A02 cells in culture for 72 hours. In conclusion, the mechanism of Tet and DRL reversing multidrug resistance has no correlation with the apoptosis of K562/A02 cells.

Alkaloids↗